Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common substrate, such as a silicon substrate, through microfabrication technology. While the electronics are fabricated using integrated circuit (IC) process sequences (e.g., CMOS, Bipolar, or BICMOS processes), the micromechanical components are fabricated using compatible “micromachining” processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices.
A MEMS device includes small structures with dimensions in the micrometer scale (one millionth of a meter). Significant portions of the MEMS technology have been adopted from integrated circuit (IC) technology. For instance, similar to ICs, MEMS structures are, in general, realized in thin films of materials and patterned with photolithographic methods. Moreover, similar to ICs, MEMS structures are, in general, fabricated on a wafer by a sequence of deposition, lithography and etching.
With the increasing complexity of MEMS structures, the fabrication process of a MEMS device also becomes increasingly complex. For example, an array of MEMS probes can be assembled on an application platform of a probe card. A probe card is an interface between an electronic test system and a semiconductor wafer under test. A probe card provides an electrical path between the test system and the circuitry on the wafer, thereby enabling the testing and validation of the circuitry at the wafer level, before the chips on the wafer are diced and packaged.
A probe card typically contains hundreds to tens of thousands of probes on a single platform. Therefore, the spacing between two neighboring probes is usually in the range of 0.1 mm or less. During the probe assembly process, the tight spacing between the probes makes it difficult for a probe handling tool to grab, position and place the probes. Probe handling tools generally have dimensions comparable to or wider than the probe spacing. If the handling tool is wider than the available spacing between the probes, the handling tool cannot easily move between the probes during probe assembly without touching an adjacent probe that is already bonded to the surface of the platform. It is to be noted that a probe handling tool can be a mechanical gripper, a vacuum gripper, a magnetic gripper, or any precision tool that is capable of probe grabbing.